There are several types of previously known cushioning solutions in connection with bicycle seats, the most well-known one is the means having two helical springs at the rear end of the seat and constituting a part of the seat itself. Such helical springs have a very limited travel, at the same time as the front edge of the seat remains un-cushioned. This type of cushioning will increase comfort somewhat, but is not appropriate to accommodate the type of shock which occurs in particular in off-road bicycling.
Among recent types of cushioning for bicycle seats, a solution can be mentioned wherein the seat has a spring action in a telescopic assembly inside or along the seat tube, which tube in most bicycles is slanted in a direction down toward the crank bearing. This type of cushioning has a clear limitation in that the travel of the system along the seat tube in the spring action, is as much as 45.degree. mis-directed. This also has the effect that all attempts to obtain a long travel for such systems have not been successful, because the movement component in the wrong direction increases with an increase in the travel along the seat tube, and this becomes very noticable whenever the bumps are larger than a certain size, typically 10-15 mm.
Another previously known type of cushioning is the one in which a seat is springy by being mounted on a long and flexible arm attached to the bicycle's top tube adjacent to the handlebar bearing. This system makes it impossible to provide any bias, which leads to a tendency to swing up and down for the bicyclist during ordinary bicycling. Further, such a system has the problem that the seat will bound upwards quite far, when the bicyclist slides off the seat while moving his body rearwardly to avoid falling forward over the handlebar in a steep downhill ride, and this makes it rather difficult to get back onto the seat again afterwards. The correct distance to the pedals is achieved while the bicyclist sits on a seat which is pushed down, and without a weight on top, the seat will take a relatively high position.
From European patent application with publication number 0418429 there is known a springy saddle device for a two-wheeled vehicle, particularly for a moped or a motorcycle. An articulated system having parallel swinging arms connected to a helical spring down inside a saddle post, is attached directly to the frame, and the saddle framework is also attached directly to the swinging arms. A substantially downwardly directed movement is achieved with this device, however the device cannot be used as an optional part inserted between a standard bicycle frame and a standard seat.
A springy device for a bicycle seat is previously known from German Offenlegungsschrift number 4224941, which device is based upon a helical spring built into a seat post substitute. An adapted cylinder can slide up and down in a substantially vertical guide element behind the seat tube, and the cylindrical slide member is connected to the helical spring inside the seat post via a wire drive passing over one or more guide wheels. The seat is mounted on top of the cylindrical slide member, and thus will be able to spring substantially vertically up and down. The wire drive solution entails obvious weaknesses, and the construction does not seem particularly robust in practice.
In a situation where the bicycle rear wheel hits a bump, the whole frame and everything mounted thereto, will start to rotate around the front wheel hub of the bicycle. This causes the seat, which is situated much higher than the bicycle hubs, to move forward in the speed direction in addition to an upward movement. With a built-in option for e.g. telescopic springing down along the seat tube, as mentioned above, one further forward movement component will arise when this type of springing goes into operation, as long as the frame seat tube is slanted as is normally the case for pedal bicycles. In practice this means that the seat, in addition to travelling up an down, will also travel forward and back beneath the cyclist at any bump. If the bump is 40 mm in height, the seat will attempt to move approximately 40 mm forward and back beneath the buttocks of the cyclist. Thereby the forces involved in these movements will try to pull the bicycle in a rearward direction, while the bicyclist attempts to push the bicycle in a forward direction by producing a force against the pedals and the bicycle drive unit. Thus, the forces will appear in opposition to the bicycle propulsion. In addition, also some energy will be lost because the transfer of forces will create friction in the system due to an unfavourable attack angle. In general the cushioning effect will also be reduced. These consequences are due to the horizontal movement components which are not compensated for in previously known seat post constructions.